Analysis of the Performance and Exhaust Gas Emissions of Four HD Gaseous Fuelled Engines, Using Engine Test Data and Computer Stimulation

The performances of four lean-burn gas engines were analyzed using test data and computer simulation. Two engines have swirl initiating inlet ports leading to a high flame speed and the other two engines have no swirl motion in the combustion chamber, which results in a longer heat release.

The US Heavy Duty transient test and the 8-mode test show that hydrocarbon emissions are produced mainly at low load as well as at full load. NOx emissions are formed mainly at full load. In order to attain a minimum HC emission level, the air/fuel ratio must be adjusted accurately, especially at low load, and the valve overlap must be as small as possible, which will reduce the HC emission at part load as well as at full load.

Two computer models have been used for the analysis. When the effective efficiencies measured are corrected for the different engine specifications and settings to a reference engine, the engines considered have an almost equal indicated efficiency. The NOx emissions can be explained by the peak temperatures calculated.